Baylor researchers unravel mystery of DNA co...( HOUSTON An iconic photograph (A HRE...)

HOUSTON An iconic photograph (http://img.timeinc.net/time/80days/images/530228.jpg) of Nobel laureates Drs. Francis Crick and James Watson show the pair discussing with a rigid model of the famous double helix.

The interaction represented produced the famous explanation of the structure of DNA, but the model pictured is a stiff snapshot of idealized DNA. As researchers from Baylor College of Medicine (www.bcm.edu) and the University of Houston (www.uh.edu) note in a report that appears online in the journal Nucleic Acids Research, DNA is not a stiff or static. It is dynamic with high energy. It exists naturally in a slightly underwound state and its status changes in waves generated by normal cell functions such as DNA replication, transcription, repair and recombination. DNA is also accompanied by a cloud of counterions (charged particles that neutralize the genetic material's very negative charge) and, of course, the protein macromolecules that affect DNA activity.

"Many models and experiments have been interpreted with the static model," said Dr. Lynn Zechiedrich (http://www.bcm.edu/molvir/faculty/elz.htm), associate professor of molecular virology and microbiology at BCM and a senior author of the report. "But this model does not allow for the fact that DNA in real life is transiently underwound and overwound in its natural state."

DNA appears a perfect spring that can be stretched and then spring back to its original conformation. How far can you stretch it before something happens to the structure and it cannot bounce back? What happens when it is exposed to normal cellular stresses involved in doing its job? That was the problem that Zechiedrich and her colleagues tackled.

Their results also addresses a question posed by anot
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